Resin composition and article made therefrom

ABSTRACT

A resin composition includes 100 parts by weight of a prepolymer and 100 parts by weight to 250 parts by weight of a spherical silica prepared by vaporized metal combustion, wherein: the prepolymer is prepared by subjecting a reaction mixture to a prepolymerization reaction; the reaction mixture includes a maleimide resin, an amino-modified silicone and cyclohexanone, and relative to a total of 100 parts by weight of the maleimide resin, the amino-modified silicone and the cyclohexanone, the reaction mixture includes 60 parts by weight to 80 parts by weight of the maleimide resin, 15 parts by weight to 30 parts by weight of the amino-modified silicone and 2 parts by weight to 15 parts by weight of the cyclohexanone; the reaction mixture does not include m-aminophenol or p-aminophenol; and the amino-modified silicone has an amino equivalent of 750 g/mol to 2500 g/mol. The resin composition may be used to make various articles, such as a prepreg, a resin film, a laminate or a printed circuit board, and at least one of the following improvements can be achieved, including varnish transparency, varnish sedimentation property, glass transition temperature, X-axis coefficient of thermal expansion, T300 thermal resistance, resin cluster and resin filling property.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the priority benefits of China Patent Application No. 202111069787.3, filed on Sep. 13, 2021. The entirety the above-mentioned patent application is hereby incorporated by reference herein and made a part of this specification.

BACKGROUND 1. Field of the Disclosure

The present disclosure mainly relates to a resin composition and more particularly to a resin composition comprising a prepolymer and a spherical silica prepared by vaporized metal combustion, which is useful for preparing an article such as a prepreg, a resin film, a laminate or a printed circuit board.

2. Description of Related Art

Recently, the electronic technology has been developed towards higher density, lower power consumption and higher performance, thereby presenting more challenges to the high performance electronic materials.

Higher interconnection density per unit area of electronic devices presents more demands on the processability of circuit boards. In order to enhance the glass transition temperature, coefficient of thermal expansion, thermal resistance and the other properties of laminates, inorganic fillers are added to the resin composition. However, inorganic fillers added to the resin composition tend to settle easily, which causes unstable varnish quality; in addition, after the resin composition including inorganic fillers is subjected to wiring board lamination and resin filling processes, resin clusters may appear in the wiring board, and resin voids may appear in the wiring board after etching, which leads to poor laminate quality. Therefore, it is the concern of the industry to solve the problems associated to glass transition temperature, coefficient of thermal expansion, resin cluster and resin void so as to ensure the stability of material quality.

SUMMARY

To overcome the problems of prior arts, particularly one or more above-mentioned property demands facing conventional materials, it is a primary object of the present disclosure to provide a resin composition and an article made therefrom which may overcome at least one of the above-mentioned technical problems.

Specifically, the resin composition disclosed herein or the article made therefrom achieves improvement in one or more of the following properties: varnish transparency, varnish sedimentation property, glass transition temperature, X-axis coefficient of thermal expansion, T300 thermal resistance, resin cluster and resin filling property.

In view of the aforesaid one or more objects, in one aspect, disclosed herein is a resin composition comprising 100 parts by weight of a prepolymer and 100 parts by weight to 250 parts by weight of a spherical silica prepared by vaporized metal combustion, wherein: the prepolymer is prepared by subjecting a reaction mixture to a prepolymerization reaction; the reaction mixture comprises a maleimide resin, an amino-modified silicone and a cyclohexanone, and relative to a total of 100 parts by weight of the maleimide resin, the amino-modified silicone and the cyclohexanone, the reaction mixture comprises 60 parts by weight to 80 parts by weight of the maleimide resin, 15 parts by weight to 30 parts by weight of the amino-modified silicone and 2 parts by weight to 15 parts by weight of the cyclohexanone; the reaction mixture does not comprise m-aminophenol or p-aminophenol; and the amino-modified silicone has an amino equivalent of 750 g/mol to 2500 g/mol.

For example, in one embodiment, the maleimide resin comprises oligomer of phenylmethane maleimide, m-phenylene bismaleimide, bisphenol A diphenyl ether bismaleimide, 3,3′-dimethyl-5,5′-diethyl-4,4′-diphenyl methane bismaleimide, 4-methyl-1,3-phenylene bismaleimide, 1,6-bismaleimide-(2,2,4-trimethyl)hexane, N-2,3-xylylmaleimide, N-2,6-xylylmaleimide, N-phenylmaleimide, maleimide resin containing aliphatic long-chain structure or a combination thereof.

For example, in one embodiment, the amino-modified silicone comprises a compound of Formula (I):

-   -   in Formula (I), each R₁ independently represents a C₁-C₁₀         alkylene group, and n is an integer of 0 or greater.

For example, in one embodiment, the reaction mixture is subjected to the prepolymerization reaction at 110° C. to 140° C. for 2 to 4 hours to prepare the prepolymer.

For example, in one embodiment, the reaction mixture comprises propylene glycol monomethyl ether, ethylene glycol methyl ether acetate, propylene glycol methyl ether acetate or a combination thereof as a solvent.

For example, in one embodiment, the cyclohexanone has a conversion rate of 50% to 95% in the prepolymerization reaction.

For example, in one embodiment, the spherical silica prepared by vaporized metal combustion comprises silica having a particle size distribution D50 of less than or equal to 2.0 μm.

For example, in one embodiment, a solution of the prepolymer does not form layer separation after being stood still at room temperature for 24 hours.

For example, in one embodiment, the resin composition further comprises a cyanate ester resin, a polyolefin resin, a small molecule vinyl compound, an acrylate resin, a phenolic resin, a polyphenylene ether resin, an epoxy resin, a benzoxazine resin, a styrene maleic anhydride resin, a polyester resin, an amine curing agent, a polyamide resin, a polyimide resin, or a combination thereof.

For example, in one embodiment, the resin composition further comprises flame retardant, inorganic filler, curing accelerator, polymerization inhibitor, coloring agent, solvent, toughening agent, silane coupling agent, or a combination thereof.

For example, in one embodiment, the resin composition has a sedimentation property measured after being stood still at room temperature for 14 days of less than or equal to 0.6%.

In another aspect, the present disclosure provides an article made from the resin composition described above, which comprises a prepreg, a resin film, a laminate or a printed circuit board.

For example, in one embodiment, the resin composition disclosed herein or the article made therefrom has one, more or all of the following properties:

a glass transition temperature as measured by using dynamic mechanical analysis by reference to IPC-TM-650 2.4.24.4 of greater than or equal to 292° C.;

an X-axis coefficient of thermal expansion as measured by reference to IPC-TM-650 2.4.24.5 of less than or equal to 7.0 ppm/° C.;

the article is absent of resin cluster in a copper-free laminate made therefrom as examined by using a scanning electron microscope;

the article is absent of void in an open area of a circuit board without surface copper by visual inspection;

a varnish of the resin composition is clear and transparent after being stood still at room temperature for 30 minutes by visual inspection; and

a T300 thermal resistance as measured by using thermomechanical analysis by reference to IPC-TM-650 2.4.24.1 of greater than 70 minutes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the FTIR spectrum of the prepolymerized product and the reactant of Prepolymer Preparation Example 2.

FIG. 2 illustrates the FTIR spectrum of Prepolymer Preparation Example 2, Prepolymer Comparative Preparation Example 7 and Mixture B.

FIG. 3 compares the varnish transparency of resin compositions of Example and Comparative Example.

FIG. 4 is an SEM photograph showing a copper-free laminate sample of one Example not containing resin cluster.

FIG. 5 is an SEM photograph showing a copper-free laminate sample of one Comparative Example containing resin clusters, as circled.

FIG. 6 is a photograph showing a circuit board sample without surface copper of one Example absent of void in an open area.

FIG. 7 is a photograph showing a circuit board sample without surface copper of one Comparative Example containing void, as circled, in an open area.

DESCRIPTION OF THE EMBODIMENTS

To enable those skilled in the art to further appreciate the features and effects of the present disclosure, words and terms contained in the specification and appended claims are described and defined. Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which this disclosure pertains. In the case of conflict, the present document and definitions contained herein will control.

As used herein, the term “comprises,” “comprising,” “includes,” “including,” “encompasses,” “encompassing,” “has,” “having” or any other variant thereof is construed as an open-ended transitional phrase intended to cover a non-exclusive inclusion. For example, a composition or article of manufacture that comprises a list of elements is not necessarily limited to only those elements but may include other elements not expressly listed or inherent to such composition or article of manufacture. Further, unless expressly stated to the contrary, the term “or” refers to an inclusive or and not to an exclusive or. For example, a condition “A or B” is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present). In addition, whenever open-ended transitional phrases are used, such as “comprises,” “comprising,” “includes,” “including,” “encompasses,” “encompassing,” “has,” “having” or any other variant thereof, it is understood that transitional phrases such as “consisting essentially of” and “consisting of” are also disclosed and included.

In this disclosure, features or conditions presented as a numerical range or a percentage range are merely for convenience and brevity. Therefore, a numerical range or a percentage range should be interpreted as encompassing and specifically disclosing all possible subranges and individual numerals or values therein, particularly all integers therein. For example, a range of “1 to 8” should be understood as explicitly disclosing all subranges such as 1 to 7, 2 to 8, 2 to 6, 3 to 6, 4 to 8, 3 to 8 and so on, particularly all subranges defined by integers, as well as disclosing all individual values such as 1, 2, 3, 4, 5, 6, 7 and 8. Similarly, a range of “between 1 and 8” should be understood as explicitly disclosing all ranges such as 1 to 8, 1 to 7, 2 to 8, 2 to 6, 3 to 6, 4 to 8, 3 to 8 and so on and encompassing the end points of the ranges. Unless otherwise defined, the aforesaid interpretation rule should be applied throughout the present disclosure regardless of broadness of the scope.

Whenever amount, concentration or other numeral or parameter is expressed as a range, a preferred range or a series of upper and lower limits, it is understood that all ranges defined by any pair of the upper limit or preferred value and the lower limit or preferred value are specifically disclosed, regardless whether these ranges are explicitly described or not. In addition, unless otherwise defined, whenever a range is mentioned, the range should be interpreted as inclusive of the endpoints and every integers and fractions in the range.

Given the intended purposes and advantages of this disclosure are achieved, numerals or figures have the precision of their significant digits. For example, 40.0 should be understood as covering a range of 39.50 to 40.49.

As used herein, a Markush group or a list of items is used to describe examples or embodiments of the present disclosure. A skilled artisan will appreciate that all subgroups of members or items and individual members or items of the Markush group or list can also be used to describe the present disclosure. For example, when X is described as being “selected from a group consisting of X1, X2 and X3,” it is intended to disclose the situations of X is X1 and X is X1 and/or X2 and/or X3. In addition, when a Markush group or a list of items is used to describe examples or embodiments of the present disclosure, a skilled artisan will understand that any subgroup or any combination of the members or items in the Markush group or list may also be used to describe the present disclosure. Therefore, for example, when X is described as being “selected from a group consisting of X1, X2 and X3” and Y is described as being “selected from a group consisting of Y1, Y2 and Y3,” the disclosure includes any combination of X is X1 or X2 or X3 and Y is Y1 or Y2 or Y3. As used herein, “or a combination thereof” means “or any combination thereof”.

As used herein, unless otherwise specified, the term “resin” is a widely used common name of a synthetic polymer and is construed in the present disclosure as comprising monomer and its combination, polymer and its combination or a combination of monomer and its polymer, but not limited thereto. For example, in the present disclosure, the term “maleimide resin” is construed to encompass a maleimide monomer (a small molecule compound of maleimide), a maleimide polymer, a combination of maleimide monomers, a combination of maleimide polymers, and a combination of maleimide monomer(s) and maleimide polymer(s).

Unless otherwise specified, according to the present disclosure, a compound refers to a chemical substance formed by two or more elements bonded with chemical bonds and may comprise a small molecule compound and a polymer compound, but not limited thereto. Any compound disclosed herein is interpreted to not only include a single chemical substance but also include a class of chemical substances having the same kind of components or having the same property. In addition, as used herein, a mixture may include two or more compounds and may include a copolymer or auxiliaries, but not limited thereto.

Unless otherwise specified, according to the present disclosure, a polymer refers to the product formed by monomer(s) via polymerization and usually comprises multiple aggregates of polymers respectively formed by multiple repeated simple structure units by covalent bonds; the monomer refers to the compound forming the polymer. A polymer may comprise a homopolymer, a copolymer, a prepolymer, etc., but not limited thereto. For example, the term “diene polymer” as used herein is construed as comprising diene homopolymer, diene copolymer, diene prepolymer and diene oligomer.

A homopolymer refers to a chemical substance formed by a single compound via polymerization, addition polymerization or condensation polymerization. A copolymer refers to a chemical substance formed by two or more compounds via polymerization, addition polymerization or condensation polymerization and may comprise: random copolymers, such as a structure of -AABABBBAAABBA-; alternating copolymers, such as a structure of -ABABABAB-; graft copolymers, such as a structure of -AA(A-BBBB)AA(A-BBBB)AAA-; and block copolymers, such as a structure of -AAAAA-BBBBBB-AAAAA-.

A prepolymer refers to a product, derived from a compound or a mixture (monomer) that is subjected to prepolymerization (partial polymerization), contains unreacted reactive functional groups or has the potential to undergo further polymerization. For example, the progress of the prepolymerization reaction may be confirmed and controlled as needed by determining the molecular weight or the level of viscosity. For example, as used herein, the prepolymer of maleimide resin, amino-modified silicone and cyclohexanone refers to a product obtained by subjecting maleimide resin, amino-modified silicone and cyclohexanone to a certain degree of polymerization to achieve an intermediate molecular weight or a proper viscosity; the prepolymer contains a reactive functional group capable of participating further polymerization to obtain the final product which has been fully crosslinked or cured.

To those of ordinary skill in the art to which this disclosure pertains, a resin composition containing an additive and three compounds (e.g., A, B and C), a total of four components, is different form a resin composition containing the additive and a prepolymer formed by the three compounds (e.g., A, B and C), a total of two components, as they are completely different from each other in the aspects of preparation method, physical or chemical properties of the resin composition and properties of an article or product made therefrom. For example, the former involves mixing A, B, C and the additive to form the resin composition; in contrast, the latter involves first subjecting a reaction mixture comprising A, B and C to a prepolymerization reaction at proper conditions to form a prepolymer and then mixing the prepolymer with the additive to form the resin composition. For example, to those of ordinary skill in the art to which this disclosure pertains, the two resin compositions have completely different compositions; in addition, because the prepolymer formed by A, B and C functions completely different from A, B and C individually or collectively in the resin composition, the two resin compositions should be construed as completely different chemical substances and have completely different chemical statuses. For example, to those of ordinary skill in the art to which this disclosure pertains, because the two resin compositions are completely different chemical substances, articles made therefrom will not have the same properties. For example, to a resin composition containing a crosslinking agent and a prepolymer formed by A, B and C, since A, B and C have been partially reacted or converted during the prepolymerization reaction to form the prepolymer, during the process of heating to semi-cure the resin composition at a high temperature condition, a partial crosslinking reaction occurs between the prepolymer and the crosslinking agent but not between A, B and C individually and the crosslinking agent. As such, articles made from the two resin compositions will be completely different and have completely different properties.

The term “polymer” includes but is not limited to an oligomer. An oligomer refers to a polymer with 2-20, typically 2-5, repeating units.

Unless otherwise specified, according to the present disclosure, a modification comprises a product derived from a resin with its reactive functional group modified, a product derived from a prepolymerization reaction of a resin and other resins, a product derived from a crosslinking reaction of a resin and other resins, a product derived from homopolymerizing a resin, a product derived from copolymerizing a resin and other resins, etc.

Unless otherwise specified, an alkyl group, an alkenyl group and a hydrocarbyl group described herein are construed to encompass various isomers thereof. For example, a propyl group is construed to encompass n-propyl and iso-propyl.

Unless otherwise specified, in the present disclosure, the term “vinyl-containing” is construed to encompass the inclusion of a vinyl group, a vinylene group, an allyl group, a (meth)acrylate group or a combination thereof.

The unsaturated bond described herein, unless otherwise specified, refers to a reactive unsaturated bond, such as but not limited to an unsaturated double bond with the potential of being crosslinked with other functional groups, such as an unsaturated carbon-carbon double bond with the potential of being crosslinked with other functional groups, but not limited thereto.

Unless otherwise specified, according to the present disclosure, when the term acrylate or acrylonitrile is expressed as (meth)acrylate or (meth)acrylonitrile, it is intended to comprise both situations of containing and not containing a methyl group; for example, poly(meth)acrylate is construed as including polyacrylate and polymethacrylate. For example, (meth)acrylonitrile is construed as including acrylonitrile and methacrylonitrile.

As used herein, part(s) by weight represents weight part(s) in any weight unit, such as but not limited to kilogram, gram, pound and so on. For example, 100 parts by weight of the prepolymer may represent 100 kilograms of the prepolymer or 100 pounds of the prepolymer.

The following embodiments and examples are illustrative in nature and are not intended to limit the present disclosure and its application. In addition, the present disclosure is not bound by any theory described in the background and summary above or the following embodiments or examples. Unless otherwise specified, processes, reagents and conditions described in the examples are those known in the art.

As described above, a primary object of the present disclosure is to provide a resin composition, comprising 100 parts by weight of a prepolymer and 100 parts by weight to 250 parts by weight of a spherical silica prepared by vaporized metal combustion, wherein: the prepolymer is prepared by subjecting a reaction mixture to a prepolymerization reaction; the reaction mixture comprises a maleimide resin, an amino-modified silicone and a cyclohexanone, and relative to a total of 100 parts by weight of the maleimide resin, the amino-modified silicone and the cyclohexanone, the reaction mixture comprises 60 parts by weight to 80 parts by weight of the maleimide resin, 15 parts by weight to 30 parts by weight of the amino-modified silicone and 2 parts by weight to 15 parts by weight of the cyclohexanone; the reaction mixture does not comprise m-aminophenol or p-aminophenol; and the amino-modified silicone has an amino equivalent of 750 g/mol to 2500 g/mol.

In one embodiment, for example, unless otherwise specified, the maleimide resin used herein refers to a compound or a mixture containing at least one maleimide group. The maleimide resin used in the present disclosure is not particularly limited and may include any one or more maleimide resins useful for preparing a prepreg, a resin film, a laminate or a printed circuit board. Examples include but are not limited to oligomer of phenylmethane maleimide, m-phenylene bismaleimide, bisphenol A diphenyl ether bismaleimide, 3,3′-dimethyl-5,5′-diethyl-4,4′-diphenyl methane bismaleimide, 4-methyl-1,3-phenylene bismaleimide, 1,6-bismaleimide-(2,2,4-trimethyl)hexane, N-2,3-xylylmaleimide, N-2,6-xylylmaleimide, N-phenylmaleimide, maleimide resin containing aliphatic long-chain structure or a combination thereof, but not limited thereto.

For example, the maleimide resin may include products such as BMI-2000, BMI-2300, BMI-3000, BMI-3000H, BMI-4000H, BMI-5000, BMI-5100, BM-7000 and BMI-7000H available from Daiwakasei Co., Ltd., or products such as BMI-70 and BMI-80 available from K.I Chemical Industry Co., Ltd.

For example, the maleimide resin containing aliphatic long-chain structure may include products such as BMI-689, BMI-1400, BMI-1500, BMI-1700, BMI-2500, BMI-3000, BMI-5000 and BMI-6000 available from Designer Molecules Inc. For example, the maleimide resin containing aliphatic long chain structure may have at least one maleimide group bonded with a substituted or unsubstituted long-chain aliphatic group. The long-chain aliphatic group may be a C₅ to C₅₀ aliphatic group, such as C₁₀ to C₅₀, C₂₀ to C₅₀, C₃₀ to C₅₀, C₂₀ to C₄₀, or C₃₀ to C₄₀, but not limited thereto. Examples of commercial maleimide resins containing aliphatic long-chain structure include:

For example, in one embodiment, the amino-modified silicone disclosed herein comprises a compound of Formula (I):

In Formula (I), each R₁ independently represents a C₁-C₁₀ alkylene group, and n is an integer of 0 or greater. For example, in one embodiment, the value of n of the amino-modified silicone is not particularly limited, preferably being an integer of 1 to 64, such as 10, 20, 30, 40, 50 or 60. For example, in one embodiment, group R₁ of the amino-modified silicone may comprise a C₂-C₃ alkylene group, a C₂-C₅ alkylene group, a C₆ alkylene group, or a C₇-C₉ alkylene group, but not limited thereto.

As used herein, the amino-modified silicone has an amino equivalent of 750 g/mol to 2500 g/mol, such as 750 g/mol, 800 g/mol, 900 g/mol, 1000 g/mol, 1500 g/mol, 2200 g/mol or 2500 g/mol, but not limited thereto. Unless otherwise specified, the amino equivalent refers to the mass of the amino-modified silicone having 1 mole of amino group, in g/mol. Using the amino-modified silicone having an amino equivalent of 750 g/mol to 2500 g/mol is beneficial to achieve one or more properties including a transparent and clear varnish, lower X-axis coefficient of thermal expansion of the article made therefrom, absence of resin cluster and absence of void after resin filling.

For example, the amino-modified silicone may comprise, but not limited to, commercially available products such as X-22-161A, X-22-161B, KF-8012 and X-22-1660B-3 from Shin-Etsu Chemical Co., Ltd.

The prepolymer disclosed herein is prepared by subjecting a reaction mixture to a prepolymerization reaction, wherein the reaction mixture at least comprises a maleimide resin, an amino-modified silicone and a cyclohexanone. The amount ratio of the maleimide resin, the amino-modified silicone and the cyclohexanone is in a range of 60-80:15-30:2-15. In other words, relative to a total of 100 parts by weight of the maleimide resin, the amino-modified silicone and the cyclohexanone, the reaction mixture comprises 60 parts by weight to 80 parts by weight of the maleimide resin (such as but not limited to 60, 65, 70, 75 or 80 parts by weight), 15 parts by weight to 30 parts by weight of the amino-modified silicone (such as but not limited to 15, 20, 25 or 30 parts by weight) and 2 parts by weight to 15 parts by weight of the cyclohexanone (such as but not limited to 2, 5, 8, 10, 12 or 15 parts by weight).

In the process of preparing the prepolymer disclosed herein, m-aminophenol or p-aminophenol was not used. Inventors have found that if m-aminophenol or p-aminophenol is used in the process of preparing the prepolymer, phase separation may occur in the product solution, which may unfavorably affect one or more properties including varnish transparency, varnish sedimentation property, glass transition temperature, X-axis coefficient of thermal expansion, T300 thermal resistance and resin cluster.

For example, in one embodiment, a process of preparing the prepolymer described above includes adding the maleimide resin and the cyclohexanone to a solvent and mixing and stirring at a high temperature such as 100° C. to 110° C. After the solution is fully dissolved, the amino-modified silicone is added, and the reaction is carried out at a high temperature such as 110° C. to 140° C. for 2 to 4 hours to obtain the prepolymer of maleimide resin, amino-modified silicone and cyclohexanone.

For example, in one embodiment, the viscosity of the prepolymer as measured by using a rotational viscometer is preferably 200 to 1000 mPa·s (a.k.a. CPS).

In the process of preparing the prepolymer by prepolymerizing the maleimide resin, the amino-modified silicone and the cyclohexanone, relative to a total of 100 parts by weight of the maleimide resin, the amino-modified silicone and the cyclohexanone, the maleimide resin is 60 parts by weight to 80 parts by weight, the amino-modified silicone is 15 parts by weight to 30 parts by weight, the cyclohexanone is 2 parts by weight to 15 parts by weight, and the amount or ratio of the maleimide resin, the amino-modified silicone and the cyclohexanone may be such as 80:15:5, 78:20:2, 73:20:7, 60:25:15, 68:30:2 or 67:30:3, but not limited thereto.

For example, during the prepolymerization reaction, a carbon-carbon unsaturated double bond of the maleimide resin may react with a hydrogen atom at the α-position of the cyclohexanone in an alkaline condition or react with an amino group (—NH₂) of the amino-modified silicone. Unless otherwise specified, the hydrogen atom at the α-position refers to the hydrogen atom on the carbon atom (α-carbon) connected with the functional group (e.g., carbonyl group of the cyclohexanone).

For example, the cyclohexanone has a conversion rate of 50% to 95% in the prepolymerization reaction. Unless otherwise specified, the conversion rate of the cyclohexanone may be measured according to the weight increase method. The weight increase method involves, based on the law of conservation of mass, calculating the difference in mass between the nonvolatile reactants (such as the amino-modified silicone and the maleimide resin) before prepolymerization and the prepolymer after prepolymerization, so as to calculate the mass percentage of the cyclohexanone participating in the reaction to further obtain the conversion rate of the cyclohexanone in the prepolymerization reaction.

For example, to calculate the conversion rate of the cyclohexanone, the mass of reactants is respectively measured and recorded by using an electronic scale (accurate to 0.01 gram), the reactants including nonvolatile compounds such as maleimide resin, amino-modified silicone or p-aminophenol. A solution of the prepolymer is prepared from the process described above and then dried under vacuum at 120° C. for 2 hours to obtain a solid product, which is weighed and recorded as the mass of the prepolymerized product (solid state). The conversion rate of cyclohexanone is calculated as below:

conversion rate of cyclohexanone=[(mass of prepolymerized product−mass of nonvolatile reactants)/mass of cyclohexanone in reactants]*100%

In one embodiment, for example, the prepolymer is prepared by using, but not limited to, the following solvent: butanone (i.e., methyl ethyl ketone), toluene, dimethyl acetamide, methanol, ethanol, ethylene glycol monomethyl ether, acetone, methyl isobutyl ketone, xylene, methoxyethyl acetate, ethoxyethyl acetate, propoxyethyl acetate, ethyl acetate, ethylene glycol methyl ether acetate, dimethylformamide, propylene glycol monomethyl ether, and propylene glycol methyl ether acetate, which may be used alone or in combination. The amount of solvent may be determined according to the need of the prepolymerization reaction and is not particularly limited.

For example, in one embodiment, the spherical silica prepared by vaporized metal combustion refers to spherical silica obtained by using a vaporized metal combustion (VMC) method. The vaporized metal combustion method involves, but not limited to, using the explosive combustion of metal or metalloid powder to prepare fine spherical oxide microparticles. Specifically, silicon metal or metalloid powder may be dispersed in oxygen stream and oxidized after ignition such that heat of reaction converts the powder and oxide into vapor or liquid which may then be cooled to form the fine particles of spherical silica prepared by vaporized metal combustion.

For example, in one embodiment, the spherical silica prepared by vaporized metal combustion may have a particle size distribution D50 of less than or equal to 2.0 μm. For example, a preferred particle size distribution D50 may be between 0.2 μm and 2.0 μm. Unless otherwise specified, the particle size distribution D50 is the value of the particle diameter at 50% in the cumulative distribution of the filler, such as but not limited to spherical silica, as measured by using laser scattering.

For example, in one embodiment, the spherical silica prepared by vaporized metal combustion may be characterized by, but not limited to, having a specific surface area of 4.5 m²/g to 15 m²/g and a purity of silica content of greater than or equal to 99.8%.

For example, in one embodiment, the spherical silica prepared by vaporized metal combustion may be optionally pretreated by a silane coupling agent, such as but not limited to an amino silane coupling agent or an acrylate silane coupling agent.

In one embodiment, for example, the resin composition disclosed herein may further optionally comprise a cyanate ester resin, a polyolefin resin, a small molecule vinyl compound, an acrylate resin, a phenolic resin, a polyphenylene ether resin, an epoxy resin, a benzoxazine resin, a styrene maleic anhydride resin, a polyester resin, an amine curing agent, a polyamide resin, a polyimide resin, or a combination thereof.

The cyanate ester resin used herein may include any known cyanate ester resins used in the art, including but not limited to a cyanate ester resin with an Ar—O—C≡N structure (wherein Ar represents an aromatic group, such as benzene, naphthalene or anthracene), a phenol novolac cyanate ester resin, a bisphenol A cyanate ester resin, a bisphenol A novolac cyanate ester resin, a bisphenol F cyanate ester resin, a bisphenol F novolac cyanate ester resin, a dicyclopentadiene-containing cyanate ester resin, a naphthalene-containing cyanate ester resin, a phenolphthalein cyanate ester resin, or a combination thereof. Examples of the cyanate ester resin include but are not limited to Primaset PT-15, PT-30S, PT-60S, BA-200, BA-230S, BA-3000S, BTP-2500, BTP-6020S, DT-4000, DT-7000, ULL950S, HTL-300, CE-320, LUT-50, or LeCy available from Lonza.

For example, the polyolefin resin used herein may include any one or more polyolefin resins useful for preparing a prepreg, a resin film, a laminate or a printed circuit board. Examples include but are not limited to styrene-butadiene-divinylbenzene terpolymer, styrene-butadiene-maleic anhydride terpolymer, vinyl-polybutadiene-urethane oligomer, styrene butadiene copolymer, hydrogenated styrene butadiene copolymer, styrene isoprene copolymer, hydrogenated styrene isoprene copolymer, methylstyrene homopolymer, petroleum resin, cycloolefin copolymer and a combination thereof.

For example, the small molecule vinyl compound as used herein refers to a vinyl-containing compound with a molecular weight of less than or equal to 1000, preferably between 100 and 900 and more preferably between 100 and 800. In one embodiment, the small molecule vinyl compound may include, but not limited to, divinylbenzene, bis(vinylbenzyl) ether (BVBE), bis(vinylphenyl)ethane (BVPE), triallyl isocyanurate (TAIC), triallyl cyanurate (TAC), 1,2,4-trivinyl cyclohexane (TVCH) or a combination thereof.

For example, the acrylate resin as used herein may include, but not limited to, tricyclodecane di(meth)acrylate, tri(meth)acrylate, 1,1′-[(octahydro-4,7-methano-1H-indene-5,6-diyl)bis(methylene)]ester (e.g., SR833S, available from Sartomer) or a combination thereof.

For example, the phenolic resin used herein may be a mono-functional, bifunctional or multi-functional phenolic resin. The type of the phenolic resin is not particularly limited and may include those currently used in the field to which this disclosure pertains. Preferably, the phenolic resin is selected from a phenoxy resin, a novolac resin and a combination thereof.

For example, the polyphenylene ether resin used herein is not particularly limited and may be any one or more commercial products or a combination thereof; examples include but are not limited to dihydroxyl polyphenylene ether resin (e.g., SA90 available from SABIC), bis(vinylbenzyl) polyphenylene ether resin with a number average molecular weight of about 1200 (such as OPE-2st 1200, available from Mitsubishi Gas Chemical Co., Inc.), bis(vinylbenzyl) polyphenylene ether resin with a number average molecular weight of about 2200 (such as OPE-2st 2200, available from Mitsubishi Gas Chemical Co., Inc.), vinyl-benzylated modified bisphenol A polyphenylene ether resin, methacrylic polyphenylene ether resin (e.g., SA9000 available from SABIC), amino-terminated polyphenylene ether resin, maleimide- or maleic anhydride-modified polyphenylene ether resin, vinyl-containing chain-extended polyphenylene ether resin with a number average molecular weight of about 2200 to 3000, or a combination thereof. The vinyl-containing chain-extended polyphenylene ether resin may include various polyphenylene ether resins disclosed in the US Patent Application Publication No. 2016/0185904 A1, all of which are incorporated herein by reference in their entirety.

For example, the epoxy resin described herein may be any one or more epoxy resins known in the field to which this disclosure pertains, including but not limited to bisphenol A epoxy resin, bisphenol F epoxy resin, bisphenol S epoxy resin, bisphenol AD epoxy resin, novolac epoxy resin, trifunctional epoxy resin, tetrafunctional epoxy resin, multifunctional epoxy resin, dicyclopentadiene (DCPD) epoxy resin, phosphorus-containing epoxy resin, p-xylene epoxy resin, naphthalene epoxy resin (e.g., naphthol epoxy resin), benzofuran epoxy resin, isocyanate-modified epoxy resin, or a combination thereof. The novolac epoxy resin may be phenol novolac epoxy resin, bisphenol A novolac epoxy resin, bisphenol F novolac epoxy resin, biphenyl novolac epoxy resin, phenol benzaldehyde epoxy resin, phenol aralkyl novolac epoxy resin or o-cresol novolac epoxy resin. The phosphorus-containing epoxy resin may be DOPO (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide) epoxy resin, DOPO-HQ epoxy resin or a combination thereof. The DOPO epoxy resin may be any one or more selected from DOPO-containing phenolic novolac epoxy resin, DOPO-containing cresol novolac epoxy resin and DOPO-containing bisphenol-A novolac epoxy resin; the DOPO-HQ epoxy resin may be any one or more selected from DOPO-HQ-containing phenolic novolac epoxy resin, DOPO-HQ-containing cresol novolac epoxy resin and DOPO-HQ-containing bisphenol-A novolac epoxy resin.

For example, the epoxy resin may be available from, but not limited to, NC-3000H (biphenyl epoxy resin) available from Nippon Kayaku, HP-7200HH (dicyclopentadiene epoxy resin) available from D.I.C. Corporation, or NPPN260 (2,6-dimethyl phenol novolac epoxy resin) available from Nan Ya Plastics Corporation.

For example, unless otherwise specified, the benzoxazine resin used in the present disclosure is not particularly limited and may include any one or more benzoxazine resins useful for making a prepreg, a resin film, a laminate or a printed circuit board. Examples include but are not limited to oxydianiline benzoxazine resin, alkenyl-containing benzoxazine resin, bisphenol A benzoxazine resin, bisphenol F benzoxazine resin, dicyclopentadiene benzoxazine resin, phenolphthalein benzoxazine resin, phosphorus-containing benzoxazine resin, and diamino benzoxazine resin. The alkenyl-containing benzoxazine resin refers to a benzoxazine resin having a carbon-carbon double bond (C═C) or a functional group derived therefrom, examples thereof including but not limited to the presence of a carbon-carbon double bond such as a vinyl group, an allyl group, a vinylbenzyl group or the like in its structure. For example, the alkenyl-containing benzoxazine resin may be allyl-modified benzoxazine resin, which may be any one or a mixture of allyl-modified bisphenol A benzoxazine resin, allyl-modified bisphenol F benzoxazine resin, allyl-modified dicyclopentadiene phenol benzoxazine resin, allyl-modified bisphenol S benzoxazine resin and diamino benzoxazine resin. The benzoxazine mixture may be for example a mixture of allyl-modified bisphenol A benzoxazine resin and allyl-modified bisphenol F benzoxazine resin; a mixture of allyl-modified dicyclopentadiene phenol benzoxazine resin and allyl-modified bisphenol S benzoxazine resin; a mixture of allyl-modified dicyclopentadiene phenol benzoxazine resin and allyl-modified bisphenol F benzoxazine resin; or a mixture of allyl-modified dicyclopentadiene phenol benzoxazine resin and allyl-modified bisphenol A benzoxazine resin. The diamino benzoxazine resin may be diaminodiphenylmethane benzoxazine resin, diaminodiphenyl sulfone benzoxazine resin, diaminodiphenyl sulfide benzoxazine resin or a combination thereof.

For example, the benzoxazine resin may include LZ-8270 (phenolphthalein benzoxazine resin), LZ-8280 (bisphenol F benzoxazine resin) or LZ-8290 (bisphenol A benzoxazine resin) available from Huntsman, PF-3500 (oxydianiline benzoxazine resin) available from Chang Chun Plastics, or HFB-2006M (phosphorus-containing benzoxazine resin) available from Showa High Polymer.

For example, the styrene maleic anhydride resin described herein may have a ratio of styrene (S) to maleic anhydride (MA) of 1:1, 2:1, 3:1, 4:1, 6:1, or 8:1, examples including but not limited to styrene maleic anhydride copolymers such as SMA-1000, SMA-2000, SMA-3000, EF-30, EF-40, EF-60 and EF-80 available from Cray Valley, or styrene maleic anhydride copolymers such as C400, C500, C700 and C900 available from Polyscope. In addition, the styrene maleic anhydride resin may also be an esterified styrene maleic anhydride copolymer, such as esterified styrene maleic anhydride copolymers SMA1440, SMA17352, SMA2625, SMA3840 and SMA31890 available from Cray Valley. Unless otherwise specified, the styrene maleic anhydride resin can be added individually or as a combination to the resin composition of this disclosure.

For example, the polyester resin used herein may be obtained by esterification of an aromatic compound with two carboxylic groups and an aromatic compound with two hydroxyl groups, such as but not limited to HPC-8000, HPC-8150 or HPC-8200 available from DIC Corporation.

For example, the amine curing agent used herein may be dicyandiamide, diamino diphenyl sulfone, diamino diphenyl methane, diamino diphenyl ether, diamino diphenyl sulfide or a combination thereof, but not limited thereto.

For example, the polyamide resin used herein may be any polyamide resin known in the field to which this disclosure pertains, including but not limited to various commercially available polyamide resin products.

For example, the polyimide resin used herein may be any polyimide resin known in the field to which this disclosure pertains, including but not limited to various commercially available polyimide resin products.

In one embodiment, for example, the resin composition disclosed herein may further optionally comprise flame retardant, inorganic filler, curing accelerator, polymerization inhibitor, coloring agent, solvent, toughening agent, silane coupling agent or a combination thereof.

For example, in one embodiment, the flame retardant used herein may be any one or more flame retardants useful for preparing a prepreg, a resin film, a laminate or a printed circuit board; examples of the flame retardant include but are not limited to a phosphorus-containing flame retardant, such as any one, two or more selected from the following group: ammonium polyphosphate, hydroquinone bis-(diphenyl phosphate), bisphenol A bis-(diphenylphosphate), tri(2-carboxyethyl) phosphine (TCEP), phosphoric acid tris(chloroisopropyl) ester, trimethyl phosphate (TMP), dimethyl methyl phosphonate (DMMP), resorcinol bis(dixylenyl phosphate) (RDXP, such as commercially available PX-200, PX-201, and PX-202), phosphazene (such as commercially available SPB-100, SPH-100, and SPV-100), melamine polyphosphate, DOPO and its derivatives or resins, diphenylphosphine oxide (DPPO) and its derivatives or resins, melamine cyanurate, tri-hydroxy ethyl isocyanurate, aluminium phosphinate (e.g., commercially available OP-930 and OP-935), or a combination thereof.

For example, the flame retardant used herein may be a DPPO (diphenyl phosphine oxide) compound (e.g., di-DPPO compound), a DOPO (9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide) compound (e.g., di-DOPO compound), a DOPO resin (e.g., DOPO-HQ, DOPO-NQ, DOPO-PN, and DOPO-BPN), and a DOPO-containing epoxy resin, etc., wherein DOPO-PN is a DOPO-containing phenol novolac compound, and DOPO-BPN may be a DOPO-containing bisphenol novolac compound, such as DOPO-BPAN (DOPO-bisphenol A novolac), DOPO-BPFN (DOPO-bisphenol F novolac) or DOPO-BPSN (DOPO-bisphenol S novolac), etc.

For example, in one embodiment, in addition to the spherical silica prepared by vaporized metal combustion, the resin composition may further comprise other inorganic filler, such as any one or more inorganic fillers used for preparing a prepreg, a resin film, a laminate or a printed circuit board; examples include but are not limited to silica (fused, non-fused, porous or hollow type), aluminum oxide, aluminum hydroxide, magnesium oxide, magnesium hydroxide, calcium carbonate, aluminum nitride, boron nitride, aluminum silicon carbide, silicon carbide, titanium dioxide, zinc oxide, zirconium oxide, mica, boehmite (A100H), calcined talc, talc, silicon nitride, and calcined kaolin. Moreover, the inorganic filler can be spherical, fibrous, plate-like, particulate, flake-like or whisker-like and can be optionally pretreated by a silane coupling agent.

In one embodiment, for example, the curing accelerator (including curing initiator) suitable for the present disclosure may comprise a catalyst, such as a Lewis base or a Lewis acid. The Lewis base may comprise any one or more of imidazole, boron trifluoride-amine complex, ethyltriphenyl phosphonium chloride, 2-methylimidazole (2MI), 2-phenyl-1H-imidazole (2PZ), 2-ethyl-4-methylimidazole (2E4MI), triphenylphosphine (TPP) and 4-dimethylaminopyridine (DMAP). The Lewis acid may comprise metal salt compounds, such as those of manganese, iron, cobalt, nickel, copper and zinc, such as zinc octanoate or cobalt octanoate. The curing accelerator also includes a curing initiator, such as a peroxide capable of producing free radicals, examples of curing initiator including but not limited to dicumyl peroxide, tert-butyl peroxybenzoate, dibenzoyl peroxide (BPO), 2,5-dimethyl-2,5-di(tert-butylperoxy)-3-hexyne (25B), bis(tert-butylperoxyisopropyl) benzene or a combination thereof.

In one embodiment, for example, the polymerization inhibitor used herein is not particularly limited and may be any polymerization inhibitor known in the field to which this disclosure pertains, including but not limited to various commercially available polymerization inhibitor products. For example, the polymerization inhibitor may comprise, but not limited to, 1,1-diphenyl-2-picrylhydrazyl radical, methyl acrylonitrile, dithioester, nitroxide-mediated radical, triphenylmethyl radical, metal ion radical, sulfur radical, hydroquinone, 4-methoxyphenol, p-benzoquinone, phenothiazine, β-phenylnaphthylamine, 4-t-butylcatechol, methylene blue, 4,4′-butylidenebis(6-t-butyl-3-methylphenol), 2,2′-methylenebis(4-ethyl-6-t-butyl phenol) or a combination thereof.

For example, the nitroxide-mediated radical may comprise, but not limited to, nitroxide radicals derived from cyclic hydroxylamines, such as 2,2,6,6-substituted piperidine 1-oxyl free radical, 2,2,5,5-substituted pyrrolidine 1-oxyl free radical or the like. Preferred substitutes include alkyl groups with 4 or fewer carbon atoms, such as methyl group or ethyl group. Examples of the compound containing a nitroxide radical include such as 2,2,6,6-tetramethylpiperidine 1-oxyl free radical, 2,2,6,6-tetraethylpiperidine 1-oxyl free radical, 2,2,6,6-tetramethyl-4-oxo-piperidine 1-oxyl free radical, 2,2,5,5-tetramethylpyrrolidine 1-oxyl free radical, 1,1,3,3-tetramethyl-2-isoindoline oxygen radical, N,N-di-tert-butylamine oxygen free radical and so on. Nitroxide radicals may also be replaced by using stable radicals such as galvinoxyl radicals.

The polymerization inhibitor suitable for the resin composition of the present disclosure may include products derived from the polymerization inhibitor with its hydrogen atom or group substituted by other atom or group. Examples include products derived from a polymerization inhibitor with its hydrogen atom substituted by an amino group, a hydroxyl group, a carbonyl group or the like.

In one embodiment, for example, the coloring agent suitable for the present disclosure may comprise, but not limited to, dye or pigment.

In one embodiment, for example, the purpose of adding solvent is to change the solid content of the resin composition and to adjust the viscosity of the resin composition. For example, the solvent may comprise, but not limited to, methanol, ethanol, ethylene glycol monomethyl ether, acetone, butanone (methyl ethyl ketone), methyl isobutyl ketone, cyclohexanone, toluene, xylene, methoxyethyl acetate, ethoxyethyl acetate, propoxyethyl acetate, ethyl acetate, dimethylformamide, dimethylacetamide, propylene glycol methyl ether, or a mixture thereof.

In one embodiment, for example, the purpose of adding toughening agent is to improve the toughness of the resin composition. The toughening agent may comprise, but not limited to, carboxyl-terminated butadiene acrylonitrile rubber (CTBN rubber), core-shell rubber, or a combination thereof.

In one embodiment, for example, the silane coupling agent used herein may comprise silane (such as but not limited to siloxane) and may be further categorized according to the functional groups into amino silane compound, epoxide silane compound, vinylsilane compound, acrylate silane compound, methacrylate silane compound, hydroxylsilane compound, isocyanate silane compound, methacryloxy silane compound and acryloxy silane compound.

The resin composition of various embodiments may be processed to make different articles, such as those suitable for use as components in electronic products, including but not limited to a prepreg, a resin film, a laminate or a printed circuit board.

For example, the resin composition from each embodiment of this disclosure can be used to make a prepreg, which comprises a reinforcement material and a layered structure disposed thereon. The layered structure is formed by heating the resin composition at a high temperature to the semi-cured state (B-stage). Suitable baking temperature for making the prepreg is 130° C. to 180° C. The reinforcement material may be any one of a fiber material, woven fabric, and non-woven fabric, and the woven fabric preferably comprises fiberglass fabrics. Types of fiberglass fabrics are not particularly limited and may be any commercial fiberglass fabric used for various printed circuit boards, such as E-glass fabric, D-glass fabric, S-glass fabric, T-glass fabric, L-glass fabric or Q-glass fabric, wherein the fiber may comprise yarns and rovings, in spread form or standard form. Non-woven fabric preferably comprises liquid crystal polymer non-woven fabric, such as polyester non-woven fabric, polyurethane non-woven fabric and so on, but not limited thereto. Woven fabric may also comprise liquid crystal polymer woven fabric, such as polyester woven fabric, polyurethane woven fabric and so on, but not limited thereto. The reinforcement material may increase the mechanical strength of the prepreg. In one preferred embodiment, the reinforcement material can be optionally pre-treated by a silane coupling agent. The prepreg may be further heated and cured to the C-stage to form an insulation layer.

For example, the resin composition from each embodiment of this disclosure can be used to make a resin film, which is prepared by heating and baking to semi-cure the resin composition. The resin composition may be selectively coated on a polyethylene terephthalate film (PET film), a polyimide film (PI film), a copper foil or a resin-coated copper, followed by heating and baking to semi-cure the resin composition to form the resin film.

For example, the resin composition from each embodiment of this disclosure can be used to make a laminate, which comprises two metal foils and an insulation layer disposed between the metal foils, wherein the insulation layer is made by curing the resin composition at high temperature and high pressure to the C-stage, a suitable curing temperature being for example between 230° C. and 250° C. and preferably between 235° C. and 245° C. and a suitable curing time being 80 to 180 minutes and preferably 100 to 150 minutes. The insulation layer may be formed by curing the aforesaid prepreg or resin film to the C-stage. The metal foil may comprise copper, aluminum, nickel, platinum, silver, gold or alloy thereof, such as a copper foil.

Preferably, the laminate is a copper-clad laminate (CCL).

In addition, the laminate may be further processed by trace formation processes to make a circuit board, such as a printed circuit board.

For example, the resin composition disclosed herein or the article made therefrom achieves improvement in one or more of the following properties: varnish transparency, varnish sedimentation property, glass transition temperature, X-axis coefficient of thermal expansion, T300 thermal resistance, resin cluster and resin filling property.

For example, the resin composition according to the present disclosure or the article made therefrom may achieve one, more or all of the following properties:

-   -   a glass transition temperature as measured by using dynamic         mechanical analysis by reference to IPC-TM-650 2.4.24.4 of         greater than or equal to 292° C., such as between 292° C. and         350° C.;     -   an X-axis coefficient of thermal expansion as measured by         reference to IPC-TM-650 2.4.24.5 of less than or equal to 7.0         ppm/° C., such as between 5.2 ppm/° C. and 7.0 ppm/° C.;     -   a T300 thermal resistance as measured by reference to IPC-TM-650         2.4.24.1 of greater than or equal to 70 minutes, such as greater         than or equal to 90 minutes, 100 minutes or 120 minutes, such as         between 70 minutes and 150 minutes;     -   the article is absent of resin cluster in a copper-free laminate         made therefrom as examined by using a scanning electron         microscope;     -   the article is absent of void in an open area of a circuit board         without surface copper by visual inspection;     -   the resin composition having a sedimentation property measured         after being stood still at room temperature for 14 days of less         than or equal to 0.6%, such as between 0.2% and 0.6%; and     -   a varnish of the resin composition being clear and transparent         after being stood still at room temperature for 30 minutes by         visual inspection.

Raw materials below are used to prepare the Prepolymer Preparation Examples and Prepolymer Comparative Preparation Examples of the present disclosure according to the amount listed in Table 1 to Table 4, and prepare the resin compositions of various Examples and Comparative Examples of the present disclosure according to the amount listed in Table 5 to Table 9 and further fabricated to prepare test samples or articles.

-   -   BMI-80: aromatic bismaleimide resin, available from K.I Chemical         Industry Co., Ltd.     -   BMI-2300: phenylmethane maleimide oligomer, available from Daiwa         Fine Chemicals Co., Ltd.     -   BMI-70: aromatic bismaleimide resin, available from K.I Chemical         Industry Co., Ltd.     -   X-22-161A: amino-modified silicone, having an amino equivalent         of 800 g/mol, available from Shin-Etsu Chemical Co., Ltd.     -   X-22-161B: amino-modified silicone, having an amino equivalent         of 1500 g/mol, available from Shin-Etsu Chemical Co., Ltd.     -   KF-8012: amino-modified silicone, having an amino equivalent of         2200 g/mol, available from Shin-Etsu Chemical Co., Ltd.     -   KF-8010: amino-modified silicone, having an amino equivalent of         430 g/mol, available from Shin-Etsu Chemical Co., Ltd.     -   KF-8008: amino-modified silicone, having an amino equivalent of         5700 g/mol, available from Shin-Etsu Chemical Co., Ltd.         cyclohexanone: boiling point 155° C., commercially available.     -   p-aminophenol: available from Shanghai Aladdin Bio-Chem         Technology Co., Ltd. DMAC: dimethyl acetamide, boiling point         164° C. to 166° C., available from Sinopec Group.     -   PM: propylene glycol monomethyl ether, boiling point 118° C. to         119° C., commercially available.     -   EGMEA: ethylene glycol methyl ether acetate, boiling point 145°         C., commercially available.     -   PMA: propylene glycol methyl ether acetate, boiling point         146° C. to 154° C., commercially available.     -   Silica A: spherical silica prepared by vaporized metal         combustion, treated by amino-containing silane coupling agent,         having a particle size distribution D50 of 0.4 μm to 0.6 μm,         product name SC-2050-MTX, available from Admatechs Company         Limited.     -   Silica B: spherical silica prepared by vaporized metal         combustion, treated by amino-containing silane coupling agent,         having a particle size distribution D50 of 0.5 μm to 1.5 μm,         available from Jinyi Silicon Materials Development Co., Ltd.     -   Silica C: spherical silica prepared by vaporized metal         combustion, treated by acrylate-containing silane coupling         agent, having a particle size distribution D50 of 0.5 μm to 1.5         μm, available from Jinyi Silicon Materials Development Co., Ltd.     -   Silica D: spherical silica prepared by microemulsion, treated by         amino-containing silane coupling agent, having a particle size         distribution D50 of 0.5 μm to 1.5 μm, available from Jinyi         Silicon Materials Development Co., Ltd.     -   Silica E: spherical silica prepared by melting, treated by         amino-containing silane coupling agent, having a particle size         distribution D50 of 2.5 μm to 3.5 μm, available from Jinyi         Silicon Materials Development Co., Ltd.     -   Silica F: non-spherical silica prepared by melting, treated by         acrylate-containing silane coupling agent, having a particle         size distribution D50 of 0.8 μm to 1.2 μm, product name FS03ARV,         available from Sibelco.     -   2PZ: 2-phenylimidazole, available from Shikoku Chemicals Corp.     -   MEK: methyl ethyl ketone, boiling point 75.6° C., commercially         available.     -   The amount of methyl ethyl ketone, dimethyl acetamide and         propylene glycol methyl ether acetate is shown as “PA” in the         Tables to indicate a “proper amount” to represent an amount of         solvents used to achieve a desirable solid content of the whole         resin composition. For a resin composition comprises methyl         ethyl ketone, dimethyl acetamide and propylene glycol methyl         ether acetate, “PA” represents the total amount of the three         solvents used to achieve a desirable solid content of the whole         resin composition, such as but not limited to a 60 wt % solid         content.

Preparation of Prepolymer

As an example, in Prepolymer Preparation Example 1, 80 parts by weight of a maleimide resin (BMI-80) and 5 parts by weight of cyclohexanone were added to a closed stirring reaction vessel containing 100 parts by weight of a solvent propylene glycol methyl ether acetate (i.e., PMA), the temperature was increased to 110° C. with stirring for 15 minutes to dissolve the maleimide resin, followed by adding 15 parts by weight of an amino-modified silicone (X-22-161B) and increasing the temperature to 120° C. and stirring and reacting for 2 hours, so as to obtain a solution of the prepolymerized product (prepolymer of maleimide resin, amino-modified silicone and cyclohexanone) of Prepolymer Preparation Example 1.

By reference to the process of Prepolymer Preparation Example 1, a maleimide resin and cyclohexanone were added to a solvent according to the amount in Table 1 to Table 4, stirring at 110° C. for 15 minutes to dissolve the maleimide resin, and adding an amino-modified silicone, followed by increasing the temperature to 120° C. and stirring and reacting for 2 hours, so as to obtain the prepolymerized product of Prepolymer Preparation Examples 2-12 and Prepolymer Comparative Preparation Examples 1-6, 13 and 14, respectively.

In Prepolymer Comparative Preparation Example 7, a maleimide resin and an amino-modified silicone were added to a solvent, the temperature was increased to 110° C. with stirring for 15 minutes to dissolve the maleimide resin, followed by increasing the temperature to 120° C. and stirring and reacting for 2 hours, so as to obtain a solution of Prepolymer Comparative Preparation Example 7.

In Prepolymer Comparative Preparation Examples 8 and 9, a maleimide resin, an amino-modified silicone and p-aminophenol were added to a solvent, the temperature was increased to 110° C. with stirring for 15 minutes to dissolve the maleimide resin, followed by increasing the temperature to 120° C. and stirring and reacting for 2 hours, so as to obtain a solution of Prepolymer Comparative Preparation Examples 8 and 9, respectively.

In Prepolymer Comparative Preparation Example 10 or 11, a maleimide resin and dimethyl acetamide or propylene glycol monomethyl ether were added to a solvent, the temperature was increased to 110° C. with stirring for 15 minutes to dissolve the maleimide resin, followed by adding an amino-modified silicone and then increasing the temperature to 120° C. and stirring and reacting for 2 hours, so as to obtain a solution of Prepolymer Comparative Preparation Example 10 or 11.

In Prepolymer Comparative Preparation Example 12, 78 parts by weight of a maleimide resin (BMI-2300) and 2 parts by weight of cyclohexanone were added to a closed stirring reaction vessel containing 100 parts by weight of cyclohexanone, the temperature was increased to 110° C. with stirring for 15 minutes to dissolve the maleimide resin, followed by adding 20 parts by weight of an amino-modified silicone (X-22-161B) and increasing the temperature to 120° C. and stirring and reacting for 2 hours, so as to obtain a solution of Prepolymer Comparative Preparation Example 12.

In addition, 78 parts by weight of a maleimide resin (BMI-80) and 2 parts by weight of cyclohexanone were added to a closed stirring reaction vessel containing 100 parts by weight of a solvent propylene glycol methyl ether acetate, the solution was stirred to fully dissolve the maleimide resin, followed by adding 20 parts by weight of an amino-modified silicone (X-22-161B) and then stirring and mixing to obtain Mixture A, which was dried under vacuum at 120° C. for 2 hours to obtain a dried Mixture A (i.e., Mixture B).

Fourier-Transform Infrared (FTIR) Spectroscopy of Prepolymer

The solution of a prepolymerized product of Prepolymer Preparation Example 2 prepared from maleimide resin, amino-modified silicone and cyclohexanone was dried under vacuum at 120° C. for 2 hours to obtain its solid from which the solvent was completely removed. FTIR spectra were tested for the solid prepolymerized product of Prepolymer Preparation Example 2, the reactants including maleimide resin, amino-modified silicone and cyclohexanone and the solvent PMA, as illustrated in FIG. 1 , showing from top to bottom the FTIR spectra of PMA, cyclohexanone, maleimide resin, amino-modified silicone and the prepolymerized product of Prepolymer Preparation Example 2, respectively. It can be observed that, in the FTIR spectrum of cyclohexanone, a —CH₂— out-of-plane bending vibration absorption peak at 1310 cm⁻¹ represents the unique absorption peak of cyclohexanone. An absorption peak also appears at 1310 cm⁻¹ in the FTIR spectrum of the prepolymerized product of Prepolymer Preparation Example 2, indicating that cyclohexanone participates in the prepolymerization reaction.

The solution of Prepolymer Comparative Preparation Example 7 was dried under vacuum at 120° C. for 2 hours to obtain its solid from which the solvent was completely removed. FTIR spectra were tested for the solid prepolymerized product of Prepolymer Preparation Example 2, the solid product of Prepolymer Comparative Preparation Example 7 and Mixture B, as illustrated in FIG. 2 , showing from top to bottom the FTIR spectra of Mixture B, solid prepolymerized product of Prepolymer Preparation Example 2 and solid product of Prepolymer Comparative Preparation Example 7, respectively. It can be observed that the absorption peak at 1310 cm⁻¹ (i.e., the unique absorption peak of cyclohexanone) appears only in the FTIR spectrum of the solid prepolymerized product of Prepolymer Preparation Example 2 and not in other FTIR spectra, indicating significant difference in structure or functional group of the product of Mixture B, Prepolymer Comparative Preparation Example 7 and Prepolymer Preparation Example 2, which further validates that cyclohexanone participates in the prepolymerization reaction.

Calculation of Conversion Rate of Cyclohexanone

To calculate the conversion rate of cyclohexanone, the mass of reactants was respectively measured and recorded by using an electronic scale (accurate to 0.01 gram), the reactants including nonvolatile compounds such as maleimide resin, amino-modified silicone or p-aminophenol. The solution from each of Prepolymer Preparation Examples 1-12 and Prepolymer Comparative Preparation Examples 1-14 was dried under vacuum at 120° C. for 2 hours to obtain a solid product, which was weighed and recorded as the mass of the prepolymerized product (solid state). The conversion rate of cyclohexanone was calculated as below and listed in Table 1 to Table 4.

conversion rate of cyclohexanone=[(mass of prepolymerized product−mass of nonvolatile reactants)/mass of cyclohexanone in reactants]*100%

Compatibility of Prepolymer

The solution from each of Prepolymer Preparation Examples 1-12 (Prep Ex 1-12) and Prepolymer Comparative Preparation Examples 1-14 (Comp Prep Ex 1-14) was loaded to a transparent volumetric flask and sealed and then stood still at room temperature for 24 hours to observe the compatibility of the solution by visual inspection. If the solution is homogeneous without phase separation, a designation of “H” is given to represent homogeneous; if layer separation or phase separation is observed from the solution, a designation of “S” is given to represent phase separation.

Test results are listed in Table 1 to Table 4 below.

TABLE 1 Raw materials and test results of Prepolymer Preparation Examples Prep Ex 1 Prep Ex 2 Prep Ex 3 Prep Ex 4 Prep Ex 5 Prep Ex 6 BMI-80 80 78 73 60 68 BMI-2300 78 BMI-70 X-22-161A X-22-161B 15 20 20 25 30 20 KF-8012 KF-8010 KF-8008 cyclohexanone 5 2 7 15 2 2 p-aminophenol DMAC PM EGMEA PMA 100 100 100 100 100 100 parts by weight of 99.00 99.90 98.00 92.50 99.90 99.90 prepolymerized product conversion rate of 80.00% 95.00% 71.43% 50.00% 95.00% 95.00% cyclohexanone compatibility test H H H H H H

TABLE 2 Raw materials and test results of Prepolymer Preparation Examples Prep Ex 7 Prep Ex 8 Prep Ex 9 Prep Ex 10 Prep Ex 11 Prep Ex 12 BMI-80 78 78 78 78 BMI-2300 BMI-70 78 67 X-22-161A 20 X-22-161B 20 30 20 20 KF-8012 20 KF-8010 KF-8008 cyclohexanone 2 3 2 2 2 2 p-aminophenol DMAC PM 100 EGMEA 30 PMA 100 100 100 100 70 parts by weight of 99.90 99.70 99.90 99.84 99.70 99.80 prepolymerized product conversion rate of 95.00% 90.00% 95.00% 92.00% 85.00% 90.00% cyclohexanone compatibility test H H H H H H

TABLE 3 Raw materials and test results of Prepolymer Comparative Preparation Examples Comp Comp Comp Comp Comp Comp Comp Prep Ex 1 Prep Ex 2 Prep Ex 3 Prep Ex 4 Prep Ex 5 Prep Ex 6 Prep Ex 7 BMI-80 83 55 60 75 79 60 78 BMI-2300 BMI-70 X-22-161A X-22-161B 15 30 35 10 20 20 22 KF-8012 KF-8010 KF-8008 cyclohexanone 2 15 5 15 1 20 p-aminophenol DMAC PM EGMEA PMA 100 100 100 100 100 100 100 parts by weight of 99.92 92.20 98.60 92.00 99.96 89.00 100.00 prepolymerized product conversion rate of 96.00% 48.00% 72.00% 46.67% 96.00% 45.00% / cyclohexanone compatibility test S H H S S H S

TABLE 4 Raw materials and test results of Prepolymer Comparative Preparation Examples Comp Comp Comp Comp Comp Comp Comp Prep Ex 8 Prep Ex 9 Prep Ex 10 Prep Ex 11 Prep Ex 12 Prep Ex 13 Prep Ex 14 BMI-80 78 78 78 78 BMI-2300 78 BMI-70 67 67 X-22-161A X-22-161B 20 20 20 KF-8012 30 KF-8010 30 20 KF-8008 20 cyclohexanone 102 2 2 p-aminophenol 3 3 DMAC 2 PM 2 EGMEA PMA 100 100 100 100 100 100 parts by weight of 100.00 100.00 98.00 98.00 110.00 99.96 99.76 prepolymerized product conversion rate of / / / / 11.76% 98.00% 88.00% cyclohexanone compatibility test S S S S H H S

In addition, Mixture A was loaded to a transparent volumetric flask and sealed and then stood still at room temperature for 24 hours. By visual inspection, layer separation and phase separation were observed from the solution, which was designated as “S” to represent phase separation.

Mixture A was dried under vacuum at 120° C. for 2 hours to obtain a dried Mixture A (i.e., Mixture B). Mixture B was weighed to obtain the amount of Mixture B as 98 parts by weight, which is the same as the total mass of nonvolatile reactants in Mixture A, i.e., 78 parts by weight of maleimide resin and 20 parts by weight of amino-modified silicone; accordingly, it can be inferred that the conversion rate of cyclohexanone in Mixture A is 0.00%.

Compositions and test results of resin compositions of Examples and Comparative Examples are listed below (in part by weight):

TABLE 5 Resin compositions of Examples (in part by weight) and test results component E1 E2 E3 E4 E5 E6 E7 E8 prepolymer Prep Ex 1 100 Prep Ex 2 100 Prep Ex 3 100 Prep Ex 4 100 Prep Ex 5 100 Prep Ex 6 100 Prep Ex 7 100 Prep Ex 8 100 Prep Ex 9 Prep Ex 10 Prep Ex 11 Prep Ex 12 amino-modified silicone X-22-161B maleimide resin BMI-80 cyclohexanone cyclohexanone filler Silica A 100 100 100 100 100 100 100 100 Silica B Silica C Silica D Silica E Silica F accelerator 2PZ 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 solvent (Sc = 60%) MEK PA PA PA PA PA PA PA PA DMAC PA PA PA PA PA PA PA PA PMA PA PA PA PA PA PA PA PA property test unit E1 E2 E3 E4 E5 E6 E7 E8 varnish transparency none CT CT CT CT CT CT CT CT varnish sedimentation % 0.2 0.3 0.4 0.3 0.4 0.5 0.4 0.2 property glass transition ° C. 342 332 324 300 312 350 310 292 temperature X-axis coefficient of ppm/° C. 7.0 6.5 6.6 6.3 5.9 6.0 6.4 6.5 thermal expansion T300 thermal resistance minute >70 >70 >70 >70 >70 >70 >70 >70 resin cluster none N N N N N N N N resin filling property none N N N N N N N N

TABLE 6 Resin compositions of Examples (in part by weight) and test results component E9 E10 E11 E12 E13 E14 E15 E16 E17 prepolymer Prep Ex 1 Prep Ex 2 100 100 100 100 100 Prep Ex 3 Prep Ex 4 Prep Ex 5 Prep Ex 6 Prep Ex 7 Prep Ex 8 Prep Ex 9 100 Prep Ex 10 100 Prep Ex 11 100 Prep Ex 12 100 amino-modified silicone X-22-161B maleimide resin BMI-80 cyclohexanone cyclohexanone filler Silica A 100 100 100 100 150 250 200 Silica B 100 Silica C 100 Silica D Silica E Silica F accelerator 2PZ 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 0.5 solvent (Sc=60%) MEK PA PA PA PA PA PA PA PA PA DMAC PA PA PA PA PA PA PA PA PA PMA PA PA PA PA PA PA PA PA PA property test unit E9 E10 E11 E12 E13 E14 E15 E16 E17 varnish transparency none CT CT CT CT CT CT CT CT CT varnish sedimentation % 0.3 0.2 0.2 0.2 0.6 0.2 0.3 0.5 0.4 property glass transition ° C. 330 320 336 330 336 340 338 330 328 temperature X-axis coefficient of ppm/° C. 6.7 7.0 6.4 6.5 6.0 5.2 5.6 6.5 6.5 thermal expansion T300 thermal resistance minute >70 >70 >70 >70 >70 >70 >70 >70 >70 resin cluster none N N N N N N N N N resin filling property none N N N N N N N N N

TABLE 7 Resin compositions of Comparative Examples (in part by weight) and test results component C1 C2 C3 C4 C5 C6 C7 prepolymer Prep Ex 1 Prep Ex 2 Prep Ex 3 Prep Ex 4 Prep Ex 5 Prep Ex 6 Prep Ex 7 Prep Ex 8 Prep Ex 9 Prep Ex 10 Prep Ex 11 Prep Ex 12 Comp Prep Ex 1 100 Comp Prep Ex 2 100 Comp Prep Ex 3 100 Comp Prep Ex 4 100 Comp Prep Ex 5 100 Comp Prep Ex 6 100 Comp Prep Ex 7 100 Comp Prep Ex 8 Comp Prep Ex 9 Comp Prep Ex 10 Comp Prep Ex 11 Comp Prep Ex 12 Comp Prep Ex 13 Comp Prep Ex 14 amino-modified silicone X-22-161B maleimide resin BMI-80 cyclohexanone cyclohexanone filler Silica A 100 100 100 100 100 100 100 Silica B Silica C Silica D Silica E Silica F accelerator 2PZ 0.5 0.5 0.5 0.5 0.5 0.5 0.5 solvent (Sc = 60%) MEK PA PA PA PA PA PA PA DMAC PA PA PA PA PA PA PA PMA PA PA PA PA PA PA PA property test unit C1 C2 C3 C4 C5 C6 C7 varnish transparency none T CT CT T T CT T varnish sedimentation % 7.0 0.2 0.6 7.0 6.0 0.3 7.0 property glass transition ° C. 342 277 279 345 326 285 320 temperature X-axis coefficient of ppm/° C. 7.3 7.0 5.5 7.6 6.6 7.5 6.5 thermal expansion T300 thermal resistance minute >70 >70 >70 >70 10 >70 10 resin cluster none Y N N Y Y N Y resin filling property none N N N N N Y N

TABLE 8 Resin compositions of Comparative Examples (in part by weight) and test results component C8 C9 C10 C11 C12 C13 C14 prepolymer Prep Ex 1 Prep Ex 2 Prep Ex 3 Prep Ex 4 Prep Ex 5 Prep Ex 6 Prep Ex 7 Prep Ex 8 Prep Ex 9 Prep Ex 10 Prep Ex 11 Prep Ex 12 Comp Prep Ex 1 Comp Prep Ex 2 Comp Prep Ex 3 Comp Prep Ex 4 Comp Prep Ex 5 Comp Prep Ex 6 Comp Prep Ex 7 Comp Prep Ex 8 100 Comp Prep Ex 9 100 Comp Prep Ex 10 100 Comp Prep Ex 11 100 Comp Prep Ex 12 100 Comp Prep Ex 13 100 Comp Prep Ex 14 100 amino-modified silicone X-22-161B maleimide resin BMI-80 cyclohexanone cyclohexanone filler Silica A 100 100 100 100 100 100 100 Silica B Silica C Silica D Silica E Silica F accelerator 2PZ 0.5 0.5 0.5 0.5 0.5 0.5 0.5 solvent (Sc = 60%) MEK PA PA PA PA PA PA PA DMAC PA PA PA PA PA PA PA PMA PA PA PA PA PA PA PA property test unit C8 C9 C10 C11 C12 C13 C14 varnish transparency none T T gelation T CT CT T varnish sedimentation % 7.0 6.0 (test 8.0 0.3 0.3 6.0 property unavailable) glass transition ° C. 280 256 320 260 280 300 temperature X-axis coefficient of ppm/° C. 7.0 8.0 6.6 7.2 8.1 7.2 thermal expansion T300 thermal resistance minute 28 20 20 >70 >70 15 resin cluster none Y Y Y N N Y resin filling property none N N N Y N Y

TABLE 9 Resin compositions of Comparative Examples (in part by weight) and test results component C15 C16 C17 C18 C19 C20 prepolymer Prep Ex 1 Prep Ex 2 100 100 100 100 100 Prep Ex 3 Prep Ex 4 Prep Ex 5 Prep Ex 6 Prep Ex 7 Prep Ex 8 Prep Ex 9 Prep Ex 10 Prep Ex 11 Prep Ex 12 Comp Prep Ex 1 Comp Prep Ex 2 Comp Prep Ex 3 Comp Prep Ex 4 Comp Prep Ex 5 Comp Prep Ex 6 Comp Prep Ex 7 Comp Prep Ex 8 Comp Prep Ex 9 Comp Prep Ex 10 Comp Prep Ex 11 Comp Prep Ex 12 Comp Prep Ex 13 Comp Prep Ex 14 amino-modified silicone X-22-161B 20 maleimide resin BMI-80 78 cyclohexanone cyclohexanone 2 filler Silica A 100 50 300 Silica B Silica C Silica D 100 Silica E 100 Silica F 100 accelerator 2PZ 0.5 0.5 0.5 0.5 0.5 0.5 solvent (Sc = 60%) MEK PA PA PA PA PA PA DMAC PA PA PA PA PA PA PMA PA PA PA PA PA PA property test unit C15 C16 C17 C18 C19 C20 varnish transparency none T T T T T T varnish sedimentation % 9.0 5.0 15.0 6.0 8.0 7.0 property glass transition ° C. 328 339 341 328 327 330 temperature X-axis coefficient of ppm/° C. 7.0 7.6 5.1 6.6 6.7 6.5 thermal expansion T300 thermal resistance minute 10 >70 >70 >70 >70 >70 resin cluster none Y Y N Y Y Y resin filling property none N N Y N N Y

Resin compositions from Table 5 to Table 9 were used to make varnishes and various samples (specimens) as described below and tested under conditions specified below so as to obtain the test results.

Varnish

Components of the resin composition from each Example (abbreviated as E1 to E17) or Comparative Example (abbreviated as C1 to C20) were placed into a stirred tank according to the amounts listed in Tables 5-9 for stirring and well-mixing to form a resin varnish.

For example, the resin composition of Example E1 was formulated by adding 100 parts by weight of the prepolymerized product from Prepolymer Preparation Example 1 to a stirrer containing a proper amount of methyl ethyl ketone, a proper amount of DMAC and a proper amount of PMA as the solvent mixture and stirred and well mixed (a proper amount of solvents is abbreviated as “PA” in Tables 5-9 to represent an amount of the solvents used to achieve a desirable solid content of the resin composition, such as a 60 wt % solid content of the varnish). Then 100 parts by weight of spherical silica prepared by vaporized metal combustion (Silica A) were added and well dispersed, followed by adding 0.5 part by weight of 2-phenyl-1H-imidazole (pre-dissolved by a proper amount of solvent) and stirring for 1 hour to obtain the varnish of resin composition E1.

In addition, according to the components and amounts listed in Table 5 to Table 9 above, varnishes of Examples E2 to E17 and Comparative Examples C1 to C20 were prepared following the preparation process of the varnish of Example E1.

Resin compositions from Table 5 to Table 9 were used to make samples (specimens) as described below and tested under conditions specified below.

Prepreg (Using 2116 E-Glass Fiber Fabric)

Resin compositions from different Examples (E1 to E17) and Comparative Examples (C1 to C20) listed in Table 5 to Table 9 were respectively added to an impregnation tank. A fiberglass fabric (e.g., 2116 E-glass fiber fabric) was passed through the impregnation tank to adhere the resin composition on the fiberglass fabric, followed by heating at 130° C. to 180° C. to the semi-cured state (B-Stage) to obtain the prepreg (resin content of about 45%).

Prepreg (Using 1027 E-Glass Fiber Fabric)

Resin compositions from different Examples (E1 to E17) and Comparative Examples (C1 to C20) listed in Table 5 to Table 9 were respectively added to an impregnation tank. A fiberglass fabric (e.g., 1027 E-glass fiber fabric) was passed through the impregnation tank to adhere the resin composition on the fiberglass fabric, followed by heating at 130° C. to 180° C. to the semi-cured state (B-Stage) to obtain the prepreg (resin content of about 73%).

Copper-Free Laminate (Obtained by Laminating Two Prepregs)

Two 18 μm reverse treatment copper foils (RTFs) and two prepregs made from each resin composition (using 2116 E-glass fiber fabrics) were prepared batchwise. Each prepreg has a resin content of about 45%. A copper foil, two prepregs and a copper foil were superimposed in such order and then subjected to a vacuum condition for lamination at 230° C. for 2 hours to form each copper-clad laminate sample. Insulation layers were formed by curing (C-stage) two sheets of superimposed prepreg between the two copper foils, and the resin content of the insulation layers was about 45%. Then each copper-clad laminate obtained above was etched for removing the two copper foils so as to obtain the copper-free laminate.

Copper-Containing Laminate (Obtained by Laminating Eight Prepregs)

Two 18 μm reverse treatment copper foils (RTFs) and eight prepregs made from each resin composition (using 2116 E-glass fiber fabrics) were prepared batchwise. Each prepreg has a resin content of about 45%. A copper foil, eight prepregs and a copper foil were superimposed in such order and then subjected to a vacuum condition for lamination at 230° C. for 2 hours to form each copper-clad laminate sample. Insulation layers were formed by curing (C-stage) eight sheets of superimposed prepreg between the two copper foils, and the resin content of the insulation layers was about 45%.

Copper-Free Laminate (Obtained by Laminating Eight Prepregs)

Each copper-containing laminate (obtained by laminating eight prepregs) obtained above was etched to remove the two copper foils so as to obtain the copper-free laminate.

Circuit Board without Surface Copper

A core was prepared as follows: preparing one prepreg (e.g., EM-390 available from Elite Material Co., Ltd., using 1078 E-glass fabric, RC=57%); a copper foil was covered on each of the two sides of the prepreg, followed by lamination and curing for 2 hours under vacuum at high temperature (195° C.) and high pressure (360 psi) to obtain a copper-containing core. Then the core was subjected to a brown oxidation and etching processes to obtain a brown oxide treated core with traces. Next, two sides on the outer layers of the brown oxide treated core with traces were respectively covered with a prepreg (using 1027 E-glass fabric) from each Example or Comparative Example and a piece of 0.5 oz (18 μm in thickness) reverse treatment copper foil (RTF), followed by lamination for 2 hours under vacuum at 230° C. to obtain a circuit board containing copper foils. Next, each circuit board was etched to remove the two copper foils to obtain a circuit board without surface copper.

Test items and test methods are described below.

1. Varnish Transparency

In the varnish transparency test, 10 mL of a varnish prepared according to the components and amounts from each Example or Comparative Example was added to a 10 mL transparent serum bottle with one side having graduation marks (labeled as the reverse side) and the other side not having graduation marks (labeled as the obverse side), and the serum bottle filled with the varnish sample was stood still at room temperature for 30 minutes and then inspected with naked eyes to determine the transparency of the varnish sample from the obverse side of the serum bottle. If the varnish sample can be seen through to observe the graduation marks on the reverse side of the serum bottle, the varnish sample is determined as clear and transparent and designated by “CT”, otherwise the varnish sample is determined as turbid and designated by “T”. Generally, a clear and transparent varnish represents high transparency of the varnish, which indicates high compatibility and flowability of the resin and filler in the sample.

For example, FIG. 3 compares the varnish transparency of resin compositions of Example and Comparative Example, which illustrates the serum bottles, No. 1 and No. 2, containing the varnish from Comparative Example and Example respectively. Observed by naked eyes, varnish sample No. 1 is turbid and has low varnish transparency, and varnish sample No. 2 is clear and transparent and has high varnish transparency.

For example, varnishes made from the resin compositions disclosed herein have excellent varnish transparency as measured by reference to the method above, such as demonstrating clear and transparent appearance in varnish transparency.

2. Varnish Sedimentation Property

In the varnish sedimentation property test, 1,000 gram of a varnish was placed in a volumetric flask with a ground stopper and stood still at room temperature for 14 days. A sampler such as a rubber head dropper was used to collect 1 gram of the varnish sample in the volumetric flask from about 3 mm below the sample surface; the sample was then dried under vacuum at 120° C. for 2 hours to obtain the solid state sample (designated as Sample A), which was weighed with an electronic scale accurate to 0.01 gram to record the mass of Sample A. Then a sampler such as a rubber head dropper was used to collect 1 gram of the varnish sample in the volumetric flask from about 3 mm above the bottom; the sample was then dried under vacuum at 120° C. for 2 hours to obtain the solid state sample (designated as Sample B), which was weighed with an electronic scale accurate to 0.01 gram to record the mass of Sample B. The absolute value of the difference in solid content between the top layer varnish and the bottom layer varnish of the same varnish was calculated as below to represent the varnish sedimentation property.

W=|(M _(A)/1)−(M _(B)/1)|×100%

-   -   wherein W is the absolute value of the difference in solid         content between the top layer varnish and the bottom layer         varnish of the same varnish and represents the varnish         sedimentation property, in %;     -   M_(A) is the mass of Sample A, in gram; and     -   M_(B) is the mass of Sample B, in gram.

From the formula for calculating the varnish sedimentation property (W), it can be inferred that a greater value in the varnish sedimentation property represents a greater difference in solid content between the top layer varnish and the bottom layer varnish of the same varnish, indicating a higher sedimentation tendency of filler in the varnish and therefore having a poor sedimentation property and providing an unstable varnish not suitable for long-term storage; in contrast, a lower value in the varnish sedimentation property represents less sedimentation of filler in the varnish, indicating a better sedimentation property and therefore providing a stable varnish suitable for long-term storage. In the test conditions described above, a value of the varnish sedimentation property of greater than or equal to 5.0% represents a poor varnish sedimentation property; a value of the varnish sedimentation property of less than or equal to 1.0% represents a great varnish sedimentation property.

For example, varnishes made from the resin composition disclosed herein have an excellent varnish sedimentation property as measured by reference to the method described above, such as a value of the varnish sedimentation property being less than or equal to 0.6%, such as less than or equal to 0.2%, 0.3%, 0.4%, 0.5% or 0.6%, such as between 0.2% and 0.6%.

3. Glass Transition Temperature (Tg)

A copper-free laminate (obtained by laminating eight prepregs) sample was subjected to glass transition temperature measurement by using the dynamic mechanical analysis (DMA) method. Each sample was heated from 35° C. to 350° C. at a heating rate of 2° C./minute and then subjected to the measurement of glass transition temperature (° C.) by reference to the method described in IPC-TM-650 2.4.24.4. Higher glass transition temperature represents a better property of the sample.

For example, articles made from the resin composition disclosed herein have a high glass transition temperature as measured by reference to IPC-TM-650 2.4.24.4, such as a glass transition temperature Tg of greater than or equal to 292° C., such as between 292° C. and 350° C.

4. X-Axis Coefficient of Thermal Expansion (CTE)

The copper-free laminate (obtained by laminating two prepregs, resin content of about 45%) sample was tested by thermal mechanical analysis (TMA) during the measurement of X-axis coefficient of thermal expansion. The copper-free laminate was cut into a sample with a length of 15 mm and a width of 2 mm having a thickness of 8 mil. Each sample was heated from 50° C. to 260° C. at a temperature increase rate of 5° C./minute and then subjected to the measurement of coefficient of thermal expansion (ppm/° C.) in X-axis in a range (al) from 40° C. to 125° C. by reference to the processes described in IPC-TM-650 2.4.24.5. Lower X-axis coefficient of thermal expansion represents a better dimensional expansion property. A difference in X-axis coefficient of thermal expansion of greater than or equal to 0.1 ppm/° C. represents a substantial difference (i.e., significant technical difficulty).

For example, articles made from the resin composition disclosed herein have a low X-axis coefficient of thermal expansion as measured by reference to IPC-TM-650 2.4.24.5, such as an X-axis coefficient of thermal expansion of less than or equal to 7.0 ppm/° C., such as less than or equal to 5.2 ppm/° C., 5.6 ppm/° C., 5.9 ppm/° C., 6.0 ppm/° C., 6.3 ppm/° C., 6.4 ppm/° C., 6.5 ppm/° C., 6.6 ppm/° C., 6.7 ppm/° C. or 7.0 ppm/° C., such as between 5.2 ppm/° C. and 7.0 ppm/° C.

5. T300 Thermal Resistance

A copper-clad laminate sample (obtained by laminating eight prepregs, 6.5 mm*6.5 mm in size) was used in the T300 thermal resistance test. At a constant temperature of 300° C., a thermal mechanical analyzer (TMA) was used by reference to IPC-TM-650 2.4.24.1 to test each sample and record the time to delamination (e.g., blistering) of the copper-clad laminate. Longer time to delamination represents better thermal resistance of the copper-clad laminate made from the resin composition. If no delamination was observed after 70 minutes of testing, a designation of “>70” was given.

For example, articles made from the resin composition disclosed herein are characterized by a time to delamination as measured by using a thermal mechanical analyzer by reference to IPC-TM-650 2.4.24.1 of greater than 70 minutes.

6. Resin Cluster of Copper-Free Laminate

A 1 cm*0.5 cm rectangular copper-free laminate (obtained by laminating eight prepregs) sample was subjected to resin filling and sectioned and then observed with a scanning electron microscope (SEM) to examine the resin cluster from the cross-section of the sample. If at least one resin cluster was found from the cross-section of the sample, the sample is designated as “Y”; otherwise, the sample is designated as “N” to represent the absence of resin cluster. Generally, the presence of resin cluster in the copper-free laminate indicates uneven distribution of filler, which may deteriorate the reliability of the laminate.

For example, FIG. 4 is an SEM photograph showing a copper-free laminate sample not containing resin cluster, and FIG. 5 is an SEM photograph showing a copper-free laminate sample containing resin clusters, wherein the seven circles in the SEM photograph represent the resin clusters.

For example, articles made from the resin composition disclosed herein are characterized by the absence of resin cluster as inspected with a scanning electron microscope.

7. Resin Filling Property of Circuit Board without Surface Copper

The aforesaid circuit board without surface copper (38.1 cm*50.4 cm) was used as the test sample. All open areas (i.e., areas with copper foil etched and removed, also known as areas without traces) of each sample were inspected with naked eyes. At least one void observed in at least one open area indicates a poor resin filling property and is designated as “Y”; absence of void in all open areas of the sample indicates a great resin filling property and is designated as “N”. Generally, more voids in the open area of a circuit board without surface copper indicates a worse resin filling property, which may more easily cause short circuit.

For example, FIG. 6 is a photograph showing a circuit board sample without surface copper of one Example not containing void in the open area, and FIG. 7 is a photograph showing a circuit board sample without surface copper of one Comparative Example containing voids in the open area, wherein the three circles in the photograph represent the voids.

For example, articles made from the resin composition disclosed herein are characterized by the absence of void in the open area as inspected according to the method described above.

The following observations can be made from Table 5 to Table 9.

A side-by-side comparison of Examples E1-E12 and Comparative Examples C1-C14 indicates that by using a prepolymer formed by reacting 60 parts by weight to 80 parts by weight of a maleimide resin, 15 parts by weight to 30 parts by weight of an amino-modified silicone and 2 parts by weight to 15 parts by weight of cyclohexanone, in contrast to using a product from the reactants different in type or amount from the above, the varnish prepared according to the present disclosure is clear and transparent and has a lower value in the varnish sedimentation property; in addition, articles made from the present disclosure can achieve at the same time one, more or all properties including a high glass transition temperature, a low X-axis coefficient of thermal expansion, a good resin filling property and the absence of resin cluster.

A side-by-side comparison of Examples E1-E17 and Comparative Examples C7-C11 indicates that by using a prepolymer formed by reacting cyclohexanone with maleimide resin and amino-modified silicone, in contrast to a prepolymer formed not by using cyclohexanone or by using other compounds in place of cyclohexanone, the varnish prepared according to the present disclosure is clear and transparent and has a lower value in the varnish sedimentation property; in addition, laminates made from the present disclosure can achieve at the same time one, more or all properties including a better T300 thermal resistance and absence of resin cluster in the copper-free laminate sample. In contrast, Comparative Examples C7-C11 fail to achieve the aforesaid desirable technical results, wherein Comparative Example C10 uses a prepolymer which is prepared with the use of catalytic DMAC such that gelation occurs in the preparation of varnish and therefore test is unavailable.

A side-by-side comparison of Examples E1-E17 and Comparative Example C15 indicates that by prepolymerizing maleimide resin, amino-modified silicone and cyclohexanone to form the prepolymer to be added to the resin composition, in contrast to adding the three components directly to the resin composition without prepolymerization, the varnish prepared according to the present disclosure is clear and transparent and has a lower value in the varnish sedimentation property; in addition, laminates made from the present disclosure can achieve at the same time one, more or all properties including a better T300 thermal resistance and absence of resin cluster in the copper-free laminate sample. In contrast, Comparative Example C15 fails to achieve the above-mentioned technical effects.

A side-by-side comparison of Examples E1-E17 and Comparative Examples C16-C20 indicates that by using 100 parts by weight to 250 parts by weight of spherical silica prepared by vaporized metal combustion, in contrast to using a silica prepared by a different process or in a different amount, the varnish prepared according to the present disclosure is clear and transparent and has a lower value in the varnish sedimentation property; in addition, laminates made from the present disclosure can achieve at the same time one, more or all properties including absence of resin cluster in the copper-free laminate and absence of void in a circuit board without surface copper after resin filling.

From the side-by-side comparison of Examples E1-E17 and Comparative Examples C1-C20, it can be confirmed that the varnish prepared by using the technical solution disclosed herein is clear and transparent and has a value of the varnish sedimentation property of less than or equal to 0.6%; in addition, laminates made from the present disclosure can achieve at the same time one, more or all properties including a glass transition temperature of greater than or equal to 292° C., an X-axis coefficient of thermal expansion of less than or equal to 7.0 ppm/° C., a T300 thermal resistance of greater than 70 minutes, absence of resin cluster in the copper-free laminate and absence of void in a circuit board without surface copper after resin filling. In contrast, Comparative Examples C1-C20 not using the technical solution of the present disclosure fail to achieve the aforesaid technical effects at the same time.

The above detailed description is merely illustrative in nature and is not intended to limit the embodiments of the subject matter or the application and uses of such embodiments. As used herein, the term “exemplary” means “serving as an example, instance, or illustration.” Any implementation described herein as exemplary is not necessarily to be construed as more preferred or advantageous over other implementations.

Moreover, while at least one exemplary example or comparative example has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary one or more embodiments described herein are not intended to limit the scope, applicability, or configuration of the claimed subject matter in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient guide for implementing the described one or more embodiments. Also, various changes can be made in the function and arrangement of elements without departing from the scope defined by the claims, which include known equivalents and all foreseeable equivalents at the time of filing this patent application. 

What is claimed is:
 1. A resin composition, comprising 100 parts by weight of a prepolymer and 100 parts by weight to 250 parts by weight of a spherical silica prepared by vaporized metal combustion, wherein: the prepolymer is prepared by subjecting a reaction mixture to a prepolymerization reaction; the reaction mixture comprises a maleimide resin, an amino-modified silicone and a cyclohexanone, and relative to a total of 100 parts by weight of the maleimide resin, the amino-modified silicone and the cyclohexanone, the reaction mixture comprises 60 parts by weight to 80 parts by weight of the maleimide resin, 15 parts by weight to 30 parts by weight of the amino-modified silicone and 2 parts by weight to 15 parts by weight of the cyclohexanone; the reaction mixture does not comprise m-aminophenol or p-aminophenol; and the amino-modified silicone has an amino equivalent of 750 g/mol to 2500 g/mol.
 2. The resin composition of claim 1, wherein the maleimide resin comprises oligomer of phenylmethane maleimide, m-phenylene bismaleimide, bisphenol A diphenyl ether bismaleimide, 3,3′-dimethyl-5,5′-diethyl-4,4′-diphenyl methane bismaleimide, 4-methyl-1,3-phenylene bismaleimide, 1,6-bismaleimide-(2,2,4-trimethyl)hexane, N-2,3-xylylmaleimide, N-2,6-xylylmaleimide, N-phenylmaleimide, maleimide resin containing aliphatic long-chain structure or a combination thereof.
 3. The resin composition of claim 1, wherein the amino-modified silicone comprises a compound of Formula (I):

wherein each R₁ independently represents a C₁-C₁₀ alkylene group, and n is an integer of 0 or greater.
 4. The resin composition of claim 1, wherein the reaction mixture is subjected to the prepolymerization reaction at 110° C. to 140° C. for 2 to 4 hours to prepare the prepolymer.
 5. The resin composition of claim 1, wherein the cyclohexanone has a conversion rate of 50% to 95% in the prepolymerization reaction.
 6. The resin composition of claim 1, wherein the spherical silica prepared by vaporized metal combustion comprises silica having a particle size distribution D50 of less than or equal to 2.0 μm.
 7. The resin composition of claim 1, wherein the reaction mixture comprises propylene glycol monomethyl ether, ethylene glycol methyl ether acetate, propylene glycol methyl ether acetate or a combination thereof as a solvent.
 8. The resin composition of claim 1, further comprising a cyanate ester resin, a polyolefin resin, a small molecule vinyl compound, an acrylate resin, a phenolic resin, a polyphenylene ether resin, an epoxy resin, a benzoxazine resin, a styrene maleic anhydride resin, a polyester resin, an amine curing agent, a polyamide resin, a polyimide resin, or a combination thereof.
 9. The resin composition of claim 1, further comprising flame retardant, inorganic filler, curing accelerator, polymerization inhibitor, coloring agent, solvent, toughening agent, silane coupling agent, or a combination thereof.
 10. The resin composition of claim 1, having a sedimentation property measured after being stood still at room temperature for 14 days of less than or equal to 0.6%.
 11. An article made from the resin composition of claim 1, comprising a prepreg, a resin film, a laminate, or a printed circuit board.
 12. The article of claim 11, having a glass transition temperature as measured by using dynamic mechanical analysis by reference to IPC-TM-650 2.4.24.4 of greater than or equal to 292° C.
 13. The article of claim 11, having an X-axis coefficient of thermal expansion as measured by reference to IPC-TM-650 2.4.24.5 of less than or equal to 7.0 ppm/° C.
 14. The article of claim 11, characterized by the absence of resin cluster in a copper-free laminate made therefrom as examined by using a scanning electron microscope.
 15. The article of claim 11, characterized by the absence of void in an open area of a circuit board without surface copper by visual inspection. 